Method for controlling the polarity of gallium nitride layers in epitaxial synthesis of GaN/AlN heterostructures on hybrid SiC/Si substrates

The effect of GaN polarity inversion from N- to Ga-face during the successive growth of GaN layers by plasma assisted molecular beam epitaxy and halide vapor phase epitaxy on hybrid SiC/Si(111) substrates was found. A new method of the formation of crack-free Ga-face GaN/AlN heterostructures on hybrid SiC/Si(111) substrates has been developed. In this method the two stage growth of GaN layers is used. At the first stage, the N-face GaN transition layer was grown on the SiC/Si(111) surface by plasma assisted molecular beam epitaxy. At the second stage, the AlN interlayer was first grown by halide vapor phase epitaxy on N-face GaN transition layer. After that the Ga-face GaN layer was synthesized by halide vapor phase epitaxy atop of the AlN interlayer. Also it was found that etching in a KOH solution affects only the N-face GaN transition layer and leads to its complete removal, which result in complete separation of the main Ga-face GaN layer from the SiC/Si(111) substrate. The method allows you to grow free from cracks and unstressed thick layers of GaN, and transfer them to the foreign substrates.